The present invention relates to a monoclonal antibody AMC-462, which belongs to the class IgG.sub.1 and reacts with digestive system cancer, and to a method of detecting the presence of digestive system cancer.
The present invention is applicable in diagnosis of digestive system cancer, especially pancreatic cancer, and effective in the field of the diagnostic.
Carcinoembryonic antigen (CEA) has been hitherto known as a tumor marker of digestive system cancer. Methods of detecting the presence of digestive system cancer by measuring CEA using anti-CEA serum (polyclonal antibody) have been known. And methods of detecting the presence of digestive system cancer using anti-CEA monoclonal antibodies have also been developed. According to the serodiagnosis by measuring CEA, the positive rate is 30-60%, and thus it is unworthy of screening of digestive system cancer patients.
Recently, in the serodiagnosis using the monoclonal antibody NS19-9 which reacts with a colorectal cancer cell line, the positive rate for pancreatic cancer and bile duct cancer amounts to nearly 80%. And in the serodiagnosis using the monoclonal antibody DuPan-2 which reacts with a pancreatic cancer cell line, the positive rate for pancreatic cancer amounts to 60-70% [Chiryogaku 15, 484 (1985)].
As mentioned above, in the serodiagnosis using the monoclonal antibodies NS19-9 and DuPan-2, the positive rate for pancreatic cancer nearly amounts to 80%, but about 20% of negative results remains. Monoclonal antibodies which are effective in respect of the 20% of negative results, if available, would be very useful in the diagnosis of pancreatic cancer.
The present inventors have found that the monoclonal antibody AMC-462 produced by a hybridoma cell line between a spleen cell obtained from a mouse immunized with human gastric cancer tissue membrane preparations and a murine myeloma cell line has a strong reactivity with digestive system cancer, especially with pancreatic cancer, and is capable of detecting the presence of digestive system cancer in respect of the samples which give negative results in the serodiagnosis using NS19-9 or DuPan-2 and have completed the present invention based on the findings.